1. Field of the Invention
The present invention relates to durable inlaid floorcoverings which are particularly suited to commercial, institutional and other heavy duty wear applications and a process for manufacturing such floorcoverings. More particularly, the invention relates to the use of spherical or essentially spherical (hereinafter "spheroidal") particles having an aspect ratio no greater than about 2:1. The spheroidal particles are provided in a dense, uniform matrix layer to create a uniformity of appearance which is superior to previously known, unpatterned, inlaid floorcovering products having similar applications.
2. Description of Related Art
Sheet materials, in particular sheet vinyl flooring products, made with particulate materials, are commonly referred to as inlaids. These products and processes for their manufacture are well known in the floorcovering art and originate back to the early linoleum times where through-patterned floorcoverings, based on linseed oil, cork dust and resins were developed by the industry. The process was later modified for vinyl.
Vinyl inlaid floorcoverings are generally made either by embedding particulate materials into a plastisol or by compacting (or sintering) particulate materials into a patterned mass. Various printing techniques are used to create desired design effects for most applications.
U.S. Pat. No. 4,212,691 to Potosky et al. discloses a method for making inlaid sheet materials using decorative chips or flakes. The chips or flakes are deposited on a layer of wet, tacky, ungelled plastisol which is optionally printed. As the chips or flakes are deposited, the ungelled plastisol is continuously moving forwardly and upwardly at an angle greater than the angle of repose for the decorative chips or flakes. At the same time, the surface of the ungelled plastisol is vibrated so that excess chips or flakes which have not adhered to the surface slide backwardly toward the place where they were deposited. The chip or flake coated surface is then processed under pressure at elevated temperatures whereby the wet, tacky, ungelled plastisol and the decorative chips or flakes are compressed into a single layer and the ungelled plastisol is transformed into a gelled plastisol.
It is difficult to obtain floorcoverings having a uniform unpatterned appearance by using the Potosky et al. materials and method. This is because of the irregularity of the chips or flakes and the unpredictable difficulties of depositing them uniformly on a wet, tacky, ungelled plastisol.
In Kaminsky, U.S. Pat. No. 4,126,727, resinous polymer sheet materials having selective decorative effects are disclosed. The sheet materials comprise a resinous polymer layer which is printed with a pattern or design having relatively dark and relatively light colored portions. The printed layer is coated with a second resinous polymer layer having decorative chips or flakes embedded therein. The decorative chips or flakes are relatively small or flat and comprise a very thin layer of transluscent or transparent platelets having a refractive index relative to surrounding material which causes certain light wave interference and color absorbtive effects. The product has a non-uniform nacreous appearance.
A well known product having commercial applications is made by the Forbo company in Gothenburg, Sweden. The product, called Smaragd, is a vinyl sheet floorcovering. Smaragd is comprised of a solid polyvinyl chloride (hereinafter "PVC") substrate reinforced with a non-woven glass fiber web. A foamable plastisol is applied in a random pattern followed by a clear vinyl coating containing evenly dispersed colored particles. The colored particles are generally low aspect ratio beads. Finally, an overcoating wearlayer of PVC is applied.
When beads (or any other kind of particles) are admixed with a liquid plastisol composition prior to application to a surface, as in the production of Smaragd, it is not possible to obtain a dense coating of particles. This is due to viscosity and other interfering factors inherent in the plastisol. As a practical matter, therefore, the maximum density of the beads is limited to about fifteen to twenty percent by weight. Total bead coverage in the final product is, therefore, effectively unattainable.
Instead of the chips, flakes, or granules heretofore generally used in the production of inlaids, it has recently been found advantageous to use spheroidal resinous particles, sometimes referred to in the art as "pearls" or "beads", for certain applications. A method for preparing such spheroidal resinous particles from plasticised PVC is disclosed in U.S. Pat. No. 3,856,900 to Erb.
Residential floorcoverings having a layer of spheroidal resinous particles in a resinous polymer layer overcoating a printed pattern or design are described in U.S. patent application Ser. No. 773,984, filed Sep. 9, 1985. The spheroidal resinous particles may be transparent, transluscent or opaque; colored or non-colored. However, at least some of them must permit the underprint to show through so that the printed pattern or design will be visible.
There is presently a demand for commercial and institutional floorcoverings having a clean, seamless, uniform, unpatterned appearance. Uniformly appearing, unpatterned floorcoverings have traditionally been the most difficult to produce, compared with those having a pattern or design. This is because slight irregularities in processing or materials used cause defects in appearance which are readily apparent, even to the untrained eye. In addition, commercial and institutional floorcoverings must meet stringent fire retardant and smoke suppressant requirements. The fire retardant and smoke suppressant compositions which must be added to such floorcoverings, however, have detrimental affects on their appearance, making them cloudy and/or dull.
It has now been found in accordance with the present invention that durable inlaid floorcoverings having a superior, uniform, unpatterned appearance, excellent wear and seaming characteristics, and superior flexibility, colorations and color durability can be produced using a dense matrix layer of spheroidal particles. Moreover, fire retardant and smoke suppressant compositions can be added without detrimentally affecting the appearance of such floorcoverings.